Sealing glass vehicle and composition and method for making same
Abstract
A sealing glass and a sealing glass paste for sealing the face plate and funnel portion of a color television tube wherein PbO-containing sealing glass frit contains from an effective amount of a powder, such as Pb 3 O 4 powder, which powder prevents the reduction of PbO to Pb metal during the sealing process, which reduction would otherwise result in a dielectric breakdown in the seal. A sealing glass paste consisting essentially of a PbO-B 2 O 3 -ZnO sealing glass frit and containing an effective amount of said powder, based upon the weight of the frit, together with hydroxypropyl cellulose binder for the frit and a solvent for the binder. A method for sealing the face plate of a color television tube to its funnel portion with a PbO-containing solder glass wherein the reduction of PbO to metallic lead during the sealing step is obviated by the addition of a sufficient amount of Pb 3 O 4 or BaO 2 powder in the solder glass and paste made therewith, which Pb 3 O 4 or BaO 2 is slowly reduced to a lower oxide in a reducing atmosphere during the sealing of the television tube components. A method for increasing the dielectric properties of a PbO-containing sealing glass paste and the devitrified seal made therefrom, which seals the face plate to the funnel of a color television tube, to a value greater than that provided by the solder glass, per se, by incorporating in the solder glass and the solder glass paste made therefrom a small but sufficient amount of Pb 3 O 4 or BaO 2 to accomplish this purpose. A vehicle for a glass frit comprises hydroxypropyl cellulose as a binder and a solvent for said binder.
Claims
exact text as granted — not AI-modifiedWe claim:
1. In a PbO containing sealing glass frit for sealing two glass surfaces together, the improvement wherein said sealing glass frit contains an inorganic nitrate, having a melting point lower than the firing temperature of the PbO containing sealing glass and a thermal decomposition temperature higher than the firing temperature of the PbO containing sealing glass, in a powder form and in an amount sufficient to prevent reduction of the PbO in said sealing glass during sealing in the presence of said reducing condition, and wherein said inorganic nitrate is compatible with the fired sealing glass, said inorganic nitrate being selected from the group consisting of LiNO 3 and AgNO 3 .
2. A PbO-containing sealing glass frit according to claim 1 having incorporated therein from about 0.1 to about 3% of said powder based upon the weight of said sealing glass frit.
3. A sealing glass frit according to claim 1 consisting essentially of: ______________________________________
CONSTITUENTS PERCENTAGE BY WEIGHT
______________________________________
PbO 75 - 82
ZnO 7 - 14
B.sub.2 O.sub.3
6.5 - 12
SiO.sub.2 1.5 - 3
______________________________________
and having incorporated therein from about 0.1 to about 3% of said powder based upon the weight of said sealing glass frit.
4. A sealing glass frit as defined in claim 3, wherein said powder is present in an amount of from about 0.2 to about 1.5% by weight of said sealing glass frit.
5. A sealing glass frit according to claim 1 in which said frit consists essentially of: ______________________________________
CONSITITUENTS PERCENT BY WEIGHT
______________________________________
PbO 75
ZnO 12.6
B.sub.2 O.sub.3
8.3
SiO.sub.2 2.1
BaO 2.
______________________________________
6. A sealing glass frit according to claim 1 in which said frit consists essentially of: ______________________________________
CONSTITUENTS PERCENT BY WEIGHT
______________________________________
PbO 84
ZnO 2.7
B.sub.2 O.sub.3
12.3
SiO.sub.2 0.4
BaO 0.6.
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